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<head><meta charset="utf-8"><title>heads up on regression · t-compiler/performance · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/247081-t-compiler/performance/index.html">t-compiler/performance</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/247081-t-compiler/performance/topic/heads.20up.20on.20regression.html">heads up on regression</a></h3>

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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/247081-t-compiler/performance/topic/heads%20up%20on%20regression/near/229105363" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nagisa <a href="https://rust-lang.github.io/zulip_archive/stream/247081-t-compiler/performance/topic/heads.20up.20on.20regression.html#229105363">(Mar 06 2021 at 15:19)</a>:</h4>
<p>Heads up, <a href="https://github.com/rust-lang/rust/pull/82806">https://github.com/rust-lang/rust/pull/82806</a> will regress compile time of a certain test case somewhat significantly, but in return it should also significantly (though hard to quantify exactly how significantly) improve runtime performance of all other rust code.</p>



<a name="229213166"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/247081-t-compiler/performance/topic/heads%20up%20on%20regression/near/229213166" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Josh Triplett <a href="https://rust-lang.github.io/zulip_archive/stream/247081-t-compiler/performance/topic/heads.20up.20on.20regression.html#229213166">(Mar 07 2021 at 19:52)</a>:</h4>
<p>Really excited to see fewer memcpy calls.</p>



<a name="229213297"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/247081-t-compiler/performance/topic/heads%20up%20on%20regression/near/229213297" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Josh Triplett <a href="https://rust-lang.github.io/zulip_archive/stream/247081-t-compiler/performance/topic/heads.20up.20on.20regression.html#229213297">(Mar 07 2021 at 19:55)</a>:</h4>
<p>I wonder if there's some more efficient IR we could emit for deep-vector rather than just a long series of zero stores. Maybe LLVM should have a single IR instruction for "big constant value"?</p>



<a name="229213346"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/247081-t-compiler/performance/topic/heads%20up%20on%20regression/near/229213346" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Josh Triplett <a href="https://rust-lang.github.io/zulip_archive/stream/247081-t-compiler/performance/topic/heads.20up.20on.20regression.html#229213346">(Mar 07 2021 at 19:55)</a>:</h4>
<p>But in any case, that regression seems reasonable. As long as it's not going strongly superlinear, it seems fine.</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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